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EP0589603A2
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EP
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Exciter circuits and methods with protective measures for solid state switches
Assignee: Unison Industries LLC
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Filing: 1993-09-14
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Granted: —
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Expires: 2013-09-14
Abstract
Abstract An exciter for an internal combustion engine igniter plug (12) comprises a continuous AC charging circuit (20) and a discharge circuit (22). The discharge circuit (22) is connectable to the plug (12) and the charging circuit (20) includes a transformer (T1) having a primary winding connectable to an AC power source (28) and a secondary winding connected to the discharge circuit. The discharge circuit includes a storage capacitor (38) connected to the transformer secondary winding such that current induced in the secondary charges the capacitor (38) at a generally constant rate. A switching device (46) is connected in series between the capacitor (38) and the plug (12). A trigger circuit (52) triggers the switching device (46) in response to charge on the capacitor (38). The charging circuit (20) and trigger circuit (52) operate to maintain a generally constant spark rate. A current multiplier (76) is also provided to substantially increase the peak currents delivered to the plug (12). A clamping diode (150) is also provided in parallel with the storage capacitor (38) to prevent reverse currents and voltages due to resonance between the capacitor (38) and stray inductance.
Inventors
- 👤 Howard Vincent Bonavia
- 👤 Dale Frank Geislinger
- 👤 Michael John Terzo
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-31 20:11
CPC Classifications
F; F02; F02P; F02P7/00; F02P7/02; F02P7/03; F02P7/035; F02P11/00; F02P15/00; F02P15/001; F02P15/003; F02P3/00; F02P3/06; F02P3/08; F02P3/0807; F02P3/0838; F02P3/0876; F02P3/0884; F02P9/00; F02P9/002
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
130 words
An exciter for an igniter, comprising an AC charging circuit (20) and a discharge circuit (22), said discharge circuit (22) being connectable to a plug (12) to cause the plug (12) to produce sparks and said charging circuit (20) being connectable to an AC power source (28), characterized in that said discharge circuit (22) comprises a storage capacitor (38) connected to said charging circuit (20) such that charging current charges said capacitor (38) at a generally constant rate between sparks, a solid state switching device (46) connected between said capacitor and the plug (12), and a trigger circuit (52) for triggering said switching device (46) in response to charge on said capacitor (38), said charging circuit (20) and said trigger circuit (52) operating to maintain a generally constant spark rate
Claim 2
Dependent Claim
43 words
An exciter according to claim 1, characterized by a half-wave rectifier (42,44) connected between said charging circuit (20) and said capacitor (38) such that alternating half-cycles of charging current are blocked thereby providing a commutation period for said switching device (46) after discharge.
Claim 3
Dependent Claim
19 words
An exciter according to claim 1, characterized in that said switching device (46) is a thyristor, GTO, or SCR.
Claim 4
Dependent Claim
37 words
An exciter according to any previous claim, characterized by a current multiplier (76) connected between said switching device (46) and the plug (12) to substantially increase current through the plug (12) to when said capacitor (38) discharges.
Claim 5
Dependent Claim
30 words
An exciter according to claim 4, characterized in that said current multiplier (76) is structurally positioned near the plug (12) to reduce power loss during discharge of said capacitor (38).
Claim 6
Dependent Claim
63 words
An exciter according to claim 4 or 5, characterized in that said current multiplier (76) comprises an autotransformer (T2) having a first winding in series between said switching device (46) and the plug (12), and a second winding connected to the plug (12) so that current applied to the plug (12) during discharge is substantially greater than current discharged from said capacitor (38).
Claim 7
Dependent Claim
21 words
An exciter according to claim 6, characterized in that said current multiplier (76) is connected to a voltage step-up circuit (T34,90).
Claim 8
Dependent Claim
79 words
An exciter according to claim 7, characterized in that said current multiplier (76) and voltage step-up circuit comprise a single core transformer having a first winding connected in series with said switching device (46) and capacitor (38), a second winding (92) connected across said plug (12) to substantially increase the voltage across the plug before an arc is struck, and a third winding connected to the plug to substantially increase current to the plug after an arc is struck.
Claim 9
Dependent Claim
18 words
An exciter according to claim 8, characterized by a diode in series between said secondary and the plug.
Claim 10
Dependent Claim
46 words
An exciter according to any previous claim, characterized in that said trigger circuit (52) comprises a comparator (54) for comparing said capacitor voltage with a reference voltage, said comparator producing a trigger signal in response to a predetermined relationship between said capacitor voltage and said reference.
Claim 11
Independent Claim
100 words
A method for producing a constant spark rate of an ingiter plug (12) in an engine, characterized by the steps of producing a half-wave rectified charging current from an AC power source (28); charging a capacitor (38) with said charging current at a generally constant rate of charge between sparks; detecting the charge on said capacitor (38); triggering a switching device (46) in response to charge on said capacitor (58) to discharge said capacitor (38) through the igniter plug (12); and turning the switching device (46) off during a non-charging half-cycle of said charging current after said capacitor (38) discharges.
Claim 12
Dependent Claim
31 words
A method according to claim 11, characterized by the step of substantially increasing current delivered to the ingiter plug (12) during discharge of the capacitor (38) using a current multiplier (76).
Claim 13
Dependent Claim
41 words
A method according to claim 12, characterized in that the step of substantially increasing the current delivered to the igniter plug (12) follows a step of substantially increasing the voltage applied to the plug (12) during discharge of said capacitor (38).
Claim 14
Dependent Claim
68 words
An exciter of the type used for supplying energy to an igniter plug and characterized by a charging circuit (20), a capacitor (38) charged by said charging circuit (20), a discharge circuit (22) having a switching device (46) for controlling the discharge of energy stored in said capacitor (38) to the plug (12), and a current multiplier (76) connected between said switching device (46) and the plug (12).
Claim 15
Dependent Claim
92 words
An exciter of the type used for supplying energy to an igniter plug (12) and characterized by a charging circuit (20), a capacitor (38) charged by said charging circuit (20), a discharge circuit (22) having two or more series-connected solid state switching devices (46) for controlling the discharge of energy stored in said capacitor (38) to the plug (12), and a snubber circuit (200) connected to each of said switching devices (46), each snubber circuit (200) comprising a capacitor (202) connected between a gate and anode of the respective switching device (46).
Claim 16
Dependent Claim
57 words
An exciter circuit for an igniter plug (12), said exciter circuit comprising a storage capacitor (38) that unidirectionally discharges through the plug (12) to produce sparks; characterized by rectifier means (150) in parallel with said capacitor (38) to prevent reverse currents and voltages by preventing resonance between said capacitor (38) and stray inductance in the exciter circuit.
Claim 17
Dependent Claim
24 words
A circuit according to claim 16, characterized in that it exhibits stray inductance primarily from internal lead length inductance and/or inductance in the capacitor.
Claim 18
Dependent Claim
36 words
A circuit according to claim 16 or 17, characterized by a second charging circuit (506), and a second rectifier means in parallel with said second capacitor for preventing respectively reverse currents and voltages across said capacitors.
Claim 19
Dependent Claim
37 words
A circuit according to claim 18, characterized in that said rectifier means (530,532) are in direct parallel relationship to the said capacitors (508,510) thereby preventing resonant circuits between said capacitors and stray inductance in the exciter circuit.
Claim 20
Independent Claim
56 words
A method of preventing reverse currents and voltages across a storage capacitor (38) in an exciter circuit for an igniter plug (12) used in a turbine engine, comprising the step of using a rectifier (150) directly in parallel with the capacitor (38) to prevent resonance between the capacitor (38) and stray inductance in the exciter circuit.
References Cited (Backward Citations)
No citation records indexed.
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